1. Field of the Invention
The invention relates to the assembly of a hub and an axle.
2. Description of the Related Art
FIG. 1 illustrates a conventional hub assembly 1 that includes an axle 13 and a hub body 11. The hub body 11 includes a base wall 111 that has opposite inner and outer surfaces 1111, 1112, a cylindrical wall 12 formed integrally with the base wall 111 and extending uprightly from the inner surface 1111, and a coupling tube 112 formed integrally on the inner surface 1111. The cylindrical wall 12 has a central axis (L) transverse to the base wall 111. The coupling tube 112 extends along the central axis (L). The axle 13 has one end retained in the coupling tube 112.
During fabrication, the axle 13 initially is disposed in a mold (not shown), which is used to form the hub body 11, at a predetermined position corresponding to the coupling tube 112. Plastic material is then injected into the mold to form the hub body 11. However, it was found that the axle 13 disposed in the mold is easily crowded by the flow of injected plastic material, thereby resulting in a deviation angle (θ) between the axle 13 and the central axis (L). Therefore, additional steps for correcting the deviation angle (θ) are needed.
FIG. 2 illustrates another conventional hub assembly 2 that includes a metal mounting cap body 22, an axle 23, and a hub body 21. The mounting cap body 22 includes a base wall 220 that has opposite inner and outer surfaces, a cylindrical wall 222 extending uprightly from the inner surface, and a coupling tube 221 formed on the inner surface at the center of the base wall 220. The axle 23 has one end riveted in the coupling tube 221. The hub body 21 is formed on the mounting cap body 22.
During fabrication, the mounting cap body 22 riveted with the axle 23 is disposed in a mold (not shown), which is used to form the hub body 21, and serves as a part of the mold. Plastic material is then injected into the mold to form the hub body 21. While the axle 23 can be precisely positioned in this manner, an additional mechanism for riveting the axle 23 to the mounting cap body 22 is needed, there by resulting in higher production costs.